Christine Ohuruogu has been left 'stunned' by the Court of Arbitration for Sport (CAS) after it rejected her appeal against a 12-month doping ban.

The 400m runner was banned for missing three drugs tests and though the CAS said there was no hint she cheated and blamed forgetfulness it upheld the ban.

"I am totally stunned by the decision," said Ohuruogu, who is ineligible to compete until 6 August this year.

"I pray other honest athletes do not end up in this devastating position."

The decision by the CAS means that Ohuruogu now faces a ban from being selected for future Olympic Games.

The British Olympic Association imposes a life ban on athletes found guilty of doping offences and Ohuruogu, 22, will now have to decide whether to lodge an appeal with them if she is to have any hope of going to the Beijing Games in 2008.

A spokesperson for Ohuruogu told the BBC that Ohuruogu was "emotional" and would wait for "things to calm down" before deciding whether to approach the BOA.

Ohuruogu was suspended by UK Athletics last August after she missed three out-of-competition drugs tests and was subsequently handed a ban in September.

The Londoner admitted committing the offence but insisted she simply forgot about the tests.

Her lawyers had argued in her CAS appeal that International Association of Athletics Federations (IAAF) sentencing guidelines are notably tougher than other sports.

We will do everything possible to get her career back on course

UKA chairman Ed Warner

Britain's world triathlon champion Tim Don received only a three-month ban for the same offence under his sport's regulations.

But CAS explained their decision in a statement which read: "The panel considered that the suspension was proportionate and should not be disturbed."

Ohuruogu added: "To be prevented from competing in the sport I love because of a lack of understanding of the system is very hard to come to terms with.

"The comment from CAS that "there is no suggestion that she is guilty of taking drugs... and, indeed, this case can be viewed in all the circumstances as a busy young athlete being forgetful', does nothing to make this situation easier to bear."

Ohuruogu has resumed training outside the UK and there is an outside chance she could win selection to represent Britain at this year's World Championships in Osaka.

The championships begin on 25 August and, though she will miss the trials the preceding month in Manchester, Ohuruogu could be chosen on training form.

UKA chairman Ed Warner said: "On completion of her suspension we will do everything possible to get her career back on course.

"Christine already holds the qualifier from last year and although it is their choice, if she can show the selectors she is competitively fit and has form, there is a chance she could be chosen.

"We will have a 4x400 metres relay squad there in which she could be included - but everything hinges on her competitive fitness."